Electric company system planners face a variety of challenges in North America and internationally to stay abreast and account for the rapid, ongoing transformation of the electric power sector. One of the specific challenges is the need for improved forecasting that reflects better integrationof customer-side behavior. The increasing penetration of distributed energy resources (DERs) and their rapid evolution has introduced a new challenge for planners to address in long-term planning models. This EPRI technical update is part of a larger EPRI project to introduce and explore methods to incorporate DERs into long-term powersystem resource planning.
Development of robust and accurate load forecasts is the starting point of any electric power company’s resource planning effort. DERs can significantly alter load levels and profiles, so improved forecasting of DER adoption would make it possible for system planners to better account for the impact of DERs on the planned system resource mix. This implies that relying on robust methods to develop adoption levels for these distributed resources and integrating them into the long-range resource plans may lead to avoided or deferred investments, reducing total system resource costs. However, while DERs may help to mitigate some system infrastructure costs, they may also require additional mitigation measures to address their intermittency (e.g., in the case of solar PVs) and increased peak capacity requirements (e.g., in the case of unmanaged EV charging). Improved DER adoption forecasts and integration methods can help increase planners’ confidence in DERs and inform ways to reduce system resource costs.
This EPRI Technical Update summarizes a comprehensive literature review designed to identify widely accepted methods used in the electric power sector to forecast adoption of rooftop solar photovoltaic resources (Rooftop PV) and electric vehicles (EV). The authors identified relevant literature on distributed solar PV and EV forecasting through consultation with EPRI subject matter experts, internet-based research, and a scan of the bibliographies of relevant reports. The studies identified in this literature review were developed by national labs, electric companies, industry research organizations, consultants, and academics. The authors reviewed 61 relevant studies, including studies focused on methods to develop solar PV and EV forecasts and published electric company Integrated Resource Plans (IRPs). The authors also identified IRPs from states with the highest levels of PV and EV penetrations to provide a more detailed look into implementations and identify prominent trends.